Geoelectric Curve Amplitude and Percentage Thickening for Aquifer Vulnerability and Hydrological Connectivity in Aquifer-Water Channel Systems: A Case Study of Akwa Ibom State

This study investigates the geoelectric properties of the aquifer system in Akwa Ibom State, Nigeria, focusing on resistivity and subsurface characteristics to understand aquifer vulnerability and hydrological connectivity. The aim is to assess the impact of resistivity inversion, saltwater intrusion, and other hydrological factors on the aquifer-water channel system in a coastal region. Methodologically, the study employs Vertical Electrical Sounding (VES), Electrical Resistivity Tomography (ERT), curve amplitude analysis, and percentage thickening metrics to evaluate aquifer depth, thickness, and resistivity across different layers. The results reveal significant variability in aquifer depths, ranging from 0.6 to 104.3 m, with resistivity in unconfined freshwater aquifers varying between 35.4 and 104.3 Ωm. Saltwater intrusion was found to reduce both resistivity and usable aquifer thickness, particularly in coastal areas such as Oron, Eket, and Ikot Abasi. Aquifer recharge inflow (56%) and discharge outflow (44%) highlight the dynamic interaction between the river and the aquifer in maintaining hydrological stability. The study also identifies high-permeability zones vulnerable to contamination, particularly from saltwater intrusion. Additional parameters, including formation factor, porosity, hydraulic conductivity, and transmissivity, further emphasize spatial variability in groundwater flow and extraction potential. The findings underscore the importance of surface water, especially near river channels, in replenishing aquifers and influencing groundwater dynamics. This research provides valuable insights for effective groundwater management in coastal regions facing environmental challenges.